Baste food often or use a source of moisture in your grill or meat smoker. Just mix some of your favorite seasonings with some water and a little vinegar. The vinegar helps tenderize the meat and the seasonings will soak into the meat together with the taste of the wood smoke. Use a basting brush to apply the basting liquid.
It keeps your BBQ food moist. The basting adds water to keep the outside of the meat from drying out. This also keeps the temperature of the meat from getting too hot while cooking.
A can of water in your BBQ grill or a pot of water in your smoker will keep your meat and fish from drying out. The water continuously provides moisture to the air surrounding the meat and therefore preventing it from drying out. The pot of water also helps deflect the heat in your smoker thereby making the heat indirect and more uniform throughout the smoking chamber. When cooking fatty meats like BBQ ribs you may want to go without basting or a water pan for the first couple of hours the render some of the fat off the meat.  Also, using a SmokePistol™ can provide lots of smoke without the excessive heat which tends to dry out meat.